I fully charged my batteries and put them in my fly more bag. The next day when I went to use one, they were noticeably warm. I hadn’t moved the bag and the room temperature was the same. Has anyone else had this issue?

They have started to self-discharge to a storage voltage level. That process generates heat. Page 25 of the manual.

MisterFrag Posted at 5-31 11:39
They have started to self-discharge to a storage voltage level. That process generates heat. Page 25 of the manual.

Thank you very much.

Hi, thank you for reaching out. You may refer to the post comment of our fellow member MisterFrag on post #3. It is normal that the battery will have a noticeable heat since the battery is starting to self-discharge. Please let us know if you have other inquiries or concerns. Thank you for your support!

Self-discharge does warm the batteries so that's a good guess
But it would be unusual if the self-discharging has started after only one day.

I have never noticed any warmth, resting or charging. Some have sat for easily more than one day. I wonder how much actual heat is generated by discharging to only 96%.